Elastomeric expansion joint for bridges and other structures

ABSTRACT

A roadway expansion joint is used in an expansion gap between adjacent sections of a bridge, parking deck, or other suitable structure to provide an uninterrupted road surface while permitting the structure to expand and contract when subjected to thermal changes. The joint is composed of a suitable elastomeric material and has a generally flat top surface with one or more exposed, tapered longitudinally-extending expansion grooves extending toward the bottom. The sides of the joint converge from the top to the bottom at an angle of between about 30* and about 60*. The bottom of the joint is parallel to and substantially narrower than the top and has one or more expansion grooves extending up therefrom, spaced laterally from the exposed grooves. Reinforcing plates are located along each side of the joint and bolt holes extend through the plate and the sides, and are spaced to coincide with studs or other fasteners extending out of the roadbed or bridge deck.

22 Filed:

United States Patent Hein [54] ELASTOMERIC EXPANSION JOINT FOR BRIDGES AND OTHER STRUCTURES [72] Inventor: Richard D. Hein, 179 Shady Lane Dr., Wabash, Ind. 46992 I Sept. 9, 1970 21 Appl.No.: 70,739

[ Sept. 12, 1972 Primary Examiner-Jacob L. Nakenoff Attorney-Frank C. Rote, Jr. and Harry F. Pepper, Jr.

[57] ABSTRACT A roadway expansion joint is used in an expansion gap between adjacent sections of a bridge, parking deck, or other suitable structure to provide an uninterrupted road surface while permitting the structure to expand and contract when subjected to thermal changes. The

' joint is composed of a suitable elastomeric material and has a generally flat top surface with one or more exposed, tapered longitudinally-extending expansion grooves extending toward the bottom. The sides of the joint converge from the top to the bottom at an angle of between about 30 and about 60. The bottom of the joint is parallel to and substantially narrower than the top and has one or more expansion grooves extending up therefrom, spaced laterally from the exposed grooves. Reinforcing plates are located along each side of the joint and bolt holes extend through the plate and the sides, and are spaced to coincide with studs or other fasteners extending out of the roadbed or bridge deck.

5Claims,5DrawingFigures PATENTEDSEP 12 1972 SHEET 2 OF 2 [NVEV/UR RICHARD D. HEIN BYEMQ-W ATTORNEY BACKGROUND OF THE INVENTION The invention relates generally to an elastomeric joint used in expansion gaps in bridges, parking decks, approaches, and other elevated structures such as overpasses. The component parts of these various structures undergo thermal expansion and contraction due to differences in ambient temperatures and gaps are provided in the bridge deck or the roadway along the width of the structure at periodic intervals to accommodate this thermal movement. Each gap may vary in width from about one-half inch to several inches depending upon the spacing between adjacent gaps and the coefficient of thermal expansion of the various components of the bridge or other structure.

,An expansion joint-is normally used to span the gap. A commonly used type of joint is called a sliding plate joint. One drawback of this joint is that it is expensive. Furthermore, it does not form a water-tight seal. Thus, water and corrosive materials, such as salt, can seep through the joint and'corrode or otherwise destroy the components of the structure beneath the bridge deck.

More. recently, various types of elastomeric seals have been suggested for use between adjacent sections of a bridge deck or between adjacent slabs of concrete in a highway. A number of these seals have been proposed, all different from one another in their size, shapeor composition. The elastomeric seal overcomes some of the problems of sliding plate joints, but it is not always completely satisfactory. One such elastomeric joint is composed of a molded rectangular slab of rubber, provided with one ormore reinforcing plates parallel to the bridge deck or roadway surface. The purpose of the reinforcingplates is to provide'vertical strength and stiffness to the joint so that vehicular traftic passing thereo'ver will not appreciably deform the expansion joint. This type of joint is typically anchored in place by embedding threaded studs in the bridge deck on either side of the expansion gap and securing the joint with nuts or the like. These studs or other fasteners must be embedded in the concrete a substantial distancefrom the edge of the gap to prevent failure of the concrete at the gap, and to ensure adequate DESCRIPTION OF THE DRAWINGS FIG. I is an isometric cross-sectional view of the joint of the present invention installed in a gap between two sections of a pavement;

FIG. 2 is a cross-sectional view taken along lines 2- 2 of FIG. 1',

FIG. 3 is an end view of one section of the joint showing a tongue-and-groove joint;

FIG. 4 is a section taken through the tongue-andgroove joint along lines 44 of FIG. 3; and

7 FIG. is a cross-section of a half of a joint showing a modification of the present invention.

DETAILED DESCRIPTION OF THE INVENTION FIGS. 1 and 2 show details of the joint 10 of the present invention. Because of the symmetry of the joint strength. Consequently, the expansion joint must be 4 considerably wider than the gap. This results in the utilization of substantially more materials of construction in the manufacture of the expansion joint than is desirable.

BRIEF DESCRIPTION OF THE INVENTION One object of the present invention is an elastomeric expansion joint that is substantially narrower than those that have been heretofore available.

Another object is a joint that is easily installed in place and that is adapted to be securely held to the bridge deck or other structure and to provide a watera tight seal therewith.

Yet another object is an elastomeric expansion joint comprising a top planar surface, a bottom surface about its vertical axis, the same reference numerals will be used to refer to and describe identical component parts. Two adjacent sections 2 of concrete are shown as cooperating to form the exposed surface of a bridge deck, parking deck, or similar structure. The two sections are separated by a gap 3 the width of which is determined by the expansion and contraction characteristics of the concrete sections and the other components of the structure. The opposed edge of each of the sections along the gap comprises a charnfered or beveled surface 4, forming an angle of between about 30 and about 60, preferably about 45 with the top surface 3 of each concrete section, and extending down therefrom to the gap 3.

As seen in FIG. 2, studs, 11 are embedded in the beveled surface 4 of the concrete and extend out at right angles therefrom. Themanner of installation of these studs is well known in the art and fomis no part of the present invention. For example, expanding anchors can be used to secure the studs in the concrete. Alternatively, a metal plate may be embedded in the concrete with the studs welded thereto. The expansion joint 10 of the present invention is anchored to the concrete by nuts 26 threaded on to bolts 13, as shown.

The joint comprises a top surface 12, a bottom surface 14, and two sides 16 converging from the top to the bottom surface at an angle corresponding to the bevel of the concrete section. The top surface is generally coplanar with the exposed surfaces of sections 2 and contains a pair of exposed expansion grooves 18 along the length of the joint, the depth of said grooves being equal to about. one-half of the thickness of the joint. These grooves are tapered, convergingly, from top to bottom, to provide self-cleaning. When foreign matter and debris get into the grooves and the expansion joint thereafter contracts, the taper of the grooves serves to expel the foreign matter and debris out of the grooves to keep the grooves clean. As molded, the portion 12a of the top surface between the two grooves 18 is slightly concave so that, upon closing of the expansion gap, this portion will not bulge appreciably above the planar surface of the bridge or parking deck.

The joint contains two reinforcing plates 22 extending along each side 16, and along the bottom 14 of the joint. Each plate is composed of two planar portions joining each other at an angle of about One portion 23 of each plate along the side provides strength to the joint where it is anchored to the concrete and distributes the stresses that are imparted to the joint by the anchors during contraction and expansion of the gap. The portion 25 of each plate along the bottom of the joint imparts beam strength to the plate and prevents the side porfion 23 of the plate from bending or bowing between adjacent anchors when the gap is open. It also provides added vertical support for the joint. The side of the joint preferably contains undulations or small grooves 27 to permit the joint to accommodate unevenness and irregularities in the beveled surfaces of the concrete sections.

As seen in FIG. 2 each stud l 1 passes up through one plate 22 into a suitable recess 24 molded into the top surface of the joint. A nut 26 is screwed onto the threaded end 13 of the stud and serves to secure the joint in the recesses of the expansion gap. The molded recess 24 is preferably of sufficient size to permit the use of a socket wrench or other appropriate installation tool to secure the joint in place. These recesses are typically located at intervals of about 12 inches along the length of the joint, to correspond with the studs set into the adjacent concrete sections.

Another longitudinal expansion groove 30 is provided in the bottom surface 14 of the expansion joint and extends up toward the top surface 12 of the joint,

terminating a short distance therefrom above the bottoms of the top grooves 18. This groove cooperates with the top expansion grooves 18 to permit the joint to flex in the lateral direction in accordian-like fashion when the gap is opened and closed. The total width of these grooves must be adequate to prevent them from closing completely when the width of the expansion gap is at a This factor, coupled with the fact that the bottom groove 30 terminates above the bottoms of the grooves 18 so that the joint does not contain any uninterrupted layer of rubber in any horizontal plane parallel to the top and bottom surfaces permits the rubber joint to flex without undergoing shear or compression deformation. Accordingly, very little pressure is required to open and close the joint. This reduces or minimizes stress forces on the joint, and on the beveled surfaces of the concrete.

The expansion joint of the present invention is typically manufactured by compression molding in sections of finite length. These sections are laid end-wise along the expansion gap. A water-tight connection is formed between adjacent sections of the joint by use of for example, a tongue-and-groove joint, as shown in FIGS. 3 and 4. One end of the expansion joint 50 contains a W- shaped groove 52 across the entire width, as shown in FIG. 3, while the opposite end of the joint is molded with a cooperating tongue. The tongue of one joint 54 (shown in outline in FIG. 4) then cooperates with groove 52 in joint 50 to form a positive connection. A suitable adhesive, such as a silicone or urethane cement, is applied to the mating surfaces to further ensure a water-tight seal.

FIG. 5 shows an alternative embodiment of the expansion joint of the present invention, particularly useful in applications where the vertical load is not appreciable or where the anchoring studs are close to one another. This joint, as the joint shown in FIGS. 1 and 2, has a top surface 112 containing longitudinally-extending expansion grooves 118, and a bottom surface 14 having an expansion groove 130, spanning the gap between adjacent sections 102 of a bridge deck, roadway, or the like. Thetwo sides 116 of the joint taper from the top to the bottom at an angle of about 45 and are reinforced with metal plates 122. Unlike the first embodiment of the invention, these plates do not extend along the bottom of the joint, but are merely coextensive with the sides 116 of the joint. Vertical support for the joint is provided by a horizontal shelf 120 formed in each section of concrete. It should be noted, however, that this support may be omitted and that the entire load may be carried by the studs and beveled surfaces. The joint is anchored in place by nuts 126 threaded on studs 111 embedded in the concrete.

The joint of the present invention has several advantages over existing expansion joints of this type. For example, the use of a chamfer or bevel along the sides of the gap, and a corresponding taper on the sides of the joint, serves to reduce spalling at the edge of the concrete along the gap since the angle of the chamfer, when it is about 45, follows the normal shear plane of the concrete under compression. This chamfer also permits the anchors to be installed in the concrete at right angle to the chamfer, thus increasing the strength and substantially reducing the total width of the joint.

As previously explained, if the anchors were installed vertically, they would have to be spaced a sufficient distance from the expansion gap to prevent weakening of the concrete in the vicinity of the gap. Consequently, the expansion joint would have to be made substantially wider than the gap to overcome this difficulty.

Because of the various grooves in the joint, the joint is easily flexed, thus permitting ease of installation. This obviates the necessity of having to utilize special tools for installing the joint. It has been found that the load required to compress a 2-inch thick, 50 Durometer joint of the present invention is about 250 pounds per lineal foot per inch of deflection, as opposed to about 1,000 pounds or more, where the rubber in the joint must be subjected to shear or to compression.

The expansion joint is inexpensive to manufacture and to maintain. Furthermore, as previously explained, it is self-cleaning, due to the tapered groves.

The joint is typically manufactured in 4 to 6 foot lengths by compression molding and curing using heat and pressure. Low carbon steel plates are used for reinforcement, and are incorporated into the joint by positioning in the mold before curing, utilizing suitable locating pins or the like. As an alternative to molding, the joint can be produced in continuous lengths by cross-head extrusion after which the joint is machined or drilled to provide apertures to receive the studs and bolts.

The joint is preferably manufactured from a natural rubber, chloroprene, butyl or ethylene-propylene terpolymer, compounded with various fillers such as carbon black and silica, along with other additives such as anti-oxidants and antiozonants, processing aids and the like. The final product should have a hardness between about 45 and about Durometer. The ultimate selection of an elastomer for the body portion of the expansion joint is normally based upon a variety of factors, such as cost, ease of fabrication, resistance to environmental elements and to ice, snow and salt, uniformity of properties over a wide temperature range, resistance to traffic wear, etc.

As previously mentioned, the sides of the elastomeric joint preferably form an angle of about 45 with the top and bottom surfaces. It should be understood that this angle can vary from about 30 to 60 while still capitalizing upon the advantages of the present invention. Of course, it is understood that the edges of the gap must be beveled to an angle that corresponds with the angle of the sides of the joint.

With the foregoing serving as an elaboration and complete explanation of the details of the present invention, but not otherwise serving as a limitation thereof, I claim:

1. A reinforced elastomeric expansion joint comprising an elastomeric body having A. a generally planar top surface including at least two transversely spaced longitudinally extending grooves each having 1. tapered sides and 2. a bottom,

B. a bottom surface including a longitudinally extending groove disposed between said at least two grooves in said top surface said groove having 1.- tapered sides and 2. a bottom disposed above the bottom of each of said at least two grooves in said top surface,

C. two side portions converging from said top surface to said bottom surface at an angle from between about 60 to about 1 20 and edge comprising a beveled surface at an angle of between about and 60 with respect to said exposed surface.

4. The combination comprising the elastomeric joint defined in claim 2 mounted between two adjacent sections of a structure providing an exposed surface along which vehicular traffic moves, said sections having opposed facing edges defining an expansion gap extending between said sections, the upper portion of each edge comprising a beveled surface at an angle of between about 30 and 60 with respect to said exposed surface.

S. The combination defined in claim 4 further including means extending through said apertures and into said sections for anchoring said joint to said structure.

GT-60l Y W105) i UNITED STATES PATENT OFFICE i CERTIFICATE OF CORRECTION v Patent NO- 3.690.226 A Dated geptembeg lg, 1912 Inventor(s) Richard I D Hein It: is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

En the heading to the printed specification, between lines 5 I and 6, the following should be inserted: Assignors to The General Tire 8c Rubber Company Signed and sealed this 17th day of April 1973 (SEAL) Attest:

. EDWARD M.'FLETCHER,JR. ROBERT GOTTSCHALK Attest ing Officer I Commissioner of Patents 

1. A reinforced elastomeric expansion joint comprising an elastomeric body having A. a generally planar top surface including at least two transversely spaced longitudinally extending grooves each having
 1. tapered sides and
 2. a bottom, B. a bottom surface including a longitudinally extending grOove disposed between said at least two grooves in said top surface said groove having
 1. tapered sides and
 2. a bottom disposed above the bottom of each of said at least two grooves in said top surface, C. two side portions converging from said top surface to said bottom surface at an angle from between about 60* to about 120* and D. reinforcing means extending longitudinally along said two sides.
 2. a bottom, B. a bottom surface including a longitudinally extending grOove disposed between said at least two grooves in said top surface said groove having
 2. a bottom disposed above the bottom of each of said at least two grooves in said top surface, C. two side portions converging from said top surface to said bottom surface at an angle from between about 60* to about 120* and D. reinforcing means extending longitudinally along said two sides.
 2. The elastomeric joint defined in claim 1 further including apertures extending generally perpendicular to the sides of said body and through said reinforcing means.
 3. The combination comprising the elastomeric joint defined in claim 1 mounted between two adjacent sections of a structure providing an exposed surface along which vehicular traffic moves, said sections having opposed facing edges defining an expansion gap extending between said sections, the upper portion of each edge comprising a beveled surface at an angle of between about 30* and 60* with respect to said exposed surface.
 4. The combination comprising the elastomeric joint defined in claim 2 mounted between two adjacent sections of a structure providing an exposed surface along which vehicular traffic moves, said sections having opposed facing edges defining an expansion gap extending between said sections, the upper portion of each edge comprising a beveled surface at an angle of between about 30* and 60* with respect to said exposed surface.
 5. The combination defined in claim 4 further including means extending through said apertures and into said sections for anchoring said joint to said structure. 